1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, the present invention relates to a two-way display-type liquid crystal display device which enables light rays radiated from one light source to simultaneously contribute to operation of upper and lower display modules, thereby restraining the number of light sources from being unnecessarily increased, and preventing a weight and a thickness thereof from being increased and assembly thereof from being complicated due to provision of an additional light source.
2. Description of the Related Art
Recently, with the advent of the information era, importance of a liquid crystal display device as one of information display devices has been increasingly emphasized.
Differently from other information display devices such as a cathode ray tube (CRT), a plasma display panel (PDP), etc., since the liquid crystal display device renders numerous advantages in terms of miniaturization, light weight, and low power consumption, it has been widely adopted and used in various information processing devices such as a notebook computer, a desktop computer, a television, a mobile communication terminal, and so on.
Referring to FIG. 1, a conventional two-way display-type liquid crystal display device 20, which is adopted in a conventional information processing device, for example, a mobile communication terminal, largely includes a light guide panel 23, upper and lower display modules 21 and 22 which are respectively positioned on an upper surface and below a lower surface of the light guide panel 23, and a printed circuit board 25 on which diverse circuit parts for driving the upper and lower display modules 21 and 22 are mounted.
A plurality of light source chips 24 are located at a side of the light guide panel 23, and separately, a light source sheet 26 is located under the printed circuit board 25. The light source chips 24 located at the side of the light guide panel 23 function to supply light rays toward the upper display module 21, and the light source sheet 26 located under the printed circuit board 25 functions to supply light rays toward the lower display module 22.
As can be readily seen from FIG. 1, a reflective sheet 27 is interposed between the light guide panel 23 and the printed circuit board 25. The reflective sheet 27 reflects light rays radiated from the light source chips 24 toward the upper display module 21 to prevent the light rays from leaking in a direction opposite to the upper display module 21. In this connection, it is the norm that the reflective sheet 27 has a reflectance approaching 100% so as to maximize the light collection rate at the upper display module 21.
In addition to the reflective sheet 27, a plurality of reflective dots (not shown) are formed on the lower surface of the light guide panel 23. The reflective dots function to scatter and reflect light rays radiated from the light source chips 24 and light rays reflected from the reflective sheet 27 toward the upper display module 21 to thereby further improve the light collection rate at the upper display module 21. Generally, each reflective dot has a size of no less than 20 xcexcm.
In the above-described construction, the upper display module 21 receives light rays radiated from the light source chips 24 by the medium of the light guide panel 23 and, using these light rays, displays main information of the information processing device, for example, in colors. The lower display module 22 directly receives light rays radiated from the light source sheet 26 and, using these light rays, displays simple auxiliary information of the information processing device, for example, in monochrome.
However, the conventional two-way display-type liquid crystal display device 20 constructed as mentioned above suffers from defects as described below.
First, since the upper and lower display modules 21 and 22 respectively employ, as their light sources, the light source chips 24 and the light source sheet 26, a thickness and a weight of the entire liquid crystal display device are increased due to a region additionally occupied by the light sources. Accordingly, it is difficult to maintain a quality of the liquid crystal display device above a predetermined level.
That is to say, in the case that the upper and lower display modules 21 and 22 respectively employ different light sources, the liquid crystal display device should be equipped with separate driving parts for driving the respective light sources, such as an inverter. Consequently, a thickness and a weight of the entire liquid display device are increased, and assembly thereof is complicated.
Meanwhile, as described above, the upper display module 21 displays, by using the light rays radiated from the light source chips 24, main information of the information processing device, in colors, as the case may be. In this color display mode, in order to ensure normal operation of the upper display module 21, light rays having a brightness which is 10 times greater than that of light rays in a monochrome display mode, are required.
However, since the light source chips 24, which contribute to a brightness of the upper display module 21, employ only the reflective dots to increase the brightness of the light rays, unless a quality of the light source chips 24 is not remarkably improved, a brightness requirement under the color display mode cannot be properly met. Consequently, the conventional liquid crystal display device cannot accomplish a display quality above a preselected level.
Moreover, because it is the norm that the conventional light source chips 24 are located at the only one side of the light guide panel 23 in the above-described conventional liquid crystal display device, one side end portion of the upper display module 21 which is distant from the light source chips 24 becomes darker than the other side end portion of the upper display module 21 which is close to the light source chips 24. As a result, brightness distribution uniformity of the upper display module 21 is deteriorated.
Of course, to cope with this problem, light source chips can be located at both sides of the light guide panel 23. However, in this case, a manufacturing cost of the liquid crystal display device is considerably increased, and a thickness and a weight of the entire liquid crystal display device are increased due to a region additionally occupied by the light source chips.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a two-way display-type liquid crystal display device which has a part layout enabling light rays radiated from one light source to simultaneously contribute to operation of upper and lower display modules, thereby restraining the number of light sources from being unnecessarily increased, and preventing a weight and a thickness thereof from being increased and assembly thereof from being complicated due to provision of an additional light source.
Another object of the present invention is to provide a two-way display-type liquid crystal display device which has a separate structure having an improved light scattering function when compared to the conventional reflective dots, thereby increasing a brightness of light rays radiated from a light source, meeting a requirement under a color display mode and improving brightness distribution uniformity.
In order to achieve the above object, according to the present invention, there is provided a two-way display-type liquid crystal display device comprising: a pair of upper and lower display modules for displaying different information; a plurality of two-way light sources for simultaneously supplying predetermined amounts of light rays to the upper and lower display modules; a light guide panel separately located at a side of the two-way light sources in a manner such that the upper and lower display modules are positioned on upper and lower surfaces of the light guide panel, respectively, the light guide panel functioning to guide light rays radiated from the two-way light sources in two directions toward the upper and lower display modules; a scattering film interposed between the light guide panel and the lower display module, for scattering and reflecting the light rays radiated from the two-way light sources toward the upper display module; and a reflective and transmissive sheet interposed between the light guide panel and the lower display module, for reflecting one part of the light rays radiated from the two-way light sources toward the upper display module and transmitting the other part of the light rays toward the lower display module.